Quantum Time Reversal Realized: Measuring to Reverse Time's Arrow and Harvest Energy

Researchers have developed quantum-control protocols that, by integrating quantum measurements with feedback, can suppress or reverse the arrow of time in quantum systems. By designing a control Hamiltonian that mirrors measurement effects, they create time-reversed or distorted trajectories and even a measurement-based engine that extracts energy from the act of observation. The work—published in Physical Review X—aims to improve quantum state control and could enable new methods for powering quantum computers and batteries, with planned experimental tests using superconducting qubits.